Core hardness tester



H. L. CAMPBELL coma HARDNESS TESTER Dec. 9, 1952 2 SHEETSSHEET 1 FiledFeb. 4, 1950 Patented Dec. 9, 1952 CORE HARDNESS TESTER Harry I3.Campbell; Oak Park, Ill., assi'gnor to Claud S..(3rord'onv Company,Chicago, 111., a. corporation of Illinois.

Application February 4, 1950', Serial No. 142,379

13 Claims. 1;

This inventionrelates to'a core-hardness tester, and more particularlyto such device in which an abrading point is moved under predeterminedpressure over a predetermined distance of travel against an exposedsurface of a baked foundry core, for ascertaining the hardness of thecore and its adaptability for making satisfactory castings for variouskinds of work.

The making of foundry cores requires skill and care in selecting theright kind of core sand, and

. the rig-ht kind and proportions of binding ma terial to be addedto thesand; suchascore coinpound; molasses water, or whatever nature ofbinding material the particular-foundry-"is using in the making ofits'cores. The-core sand and binding materials will vary in both kindand proportiomfordifferent-kinds of castings: One of the essentialrequi'rementsof foundry cores is that they have sufficient-porositytocarry" oiT the gasesgenerated the-reinby theheat of the molten metalbeing poured therearound, and at the same have adequate strengtl'itoprevent breaking or crumbling that would result inanimperfect hole inthe-casting. If thega-s generated-in the core during casting is notvented or relieved to the outside of the mold sufliciently quickly;cavities. called blow holes will be formed in the body of the casting,and possibly cause the casting to be'reie'cte'd.

For the above and other reasons, the core materials must be carefullyselected and proportioned,v asrwell as properly compressed when the coreis being formed, soas to meet themany core requirements for making goodcastings; After the cores have. been formed they are'baked in an oven;andibythe. use of the present invention one or more of the baked coresmay be selected at random" and tested to" ascertain their hardnesswhiclr'wil'li'indicatez their suitability for thepariicuiar jobin whichthey are to be used, and whether the core mix should be changed. Ifdesired avfew' test cores may he -first made, baked and tested, or suchtests may be carried outfrom time to. time. and from day to day asthefoundry work proceeds, to ascertain Whether the coremix issatisfactory. If thebaked cores are too-hard they-Will not have therequired porosity to carry the generated gases therefrom and out of themold, and if too soft they will not stand up to-the required work. Withthe present invention it is thuseasily and quickly possible to test the'baked cores to ascertain whether they meet the requirements of goodfoundry practice for'theparticular job. in which they are'tobe used.

Among the objects of this invention are: to

provide a new-and improved core hardness tester;

to provide a core hardness testerthat'is small and portable and can bereadily carried around from place to place, can be easily andconveniently manipulated, and is efficient and accurate inoperation; toprovide such tester having a stationary part within whichis mounted arotatable portion provided with an eccentric abrading element, and meansfor indicating the amount of penetration of'the abrading element intothe core after the abrading element has moved a predetermined distance,under a predetermined pressure, over the core surface; to provideacorehardness tester having means for abrading the surface of a baked core,and means for reading the'depth of abrasion to determine the hardness ofthe core; to provide a core hardness tester having an abrading elementmovableboth laterally and longitudinally, and novel means for indicatingthe amount of longitudinal movement of the abrad ing element when thetester'is operated against a baked core; and such further objects,advantages and capabilities; inherently possessed by the invention, aswill later more fully appear.

My invention further resides in the combination, construction andarrangement of parts illustrated in the accompanying drawings, and whileI have shown therein a preferred embodiment, I wish it understood thatthe same is susceptible of modification and change without departingfrom the spirit of the invention.

In. the drawings: I

Fig. l is a side elevation of my core hardness tester in the positionindicating maximum hardness of. a core upon which it had been operated;

Fig. 2 is a bottom plan view of Fig. 1;

Fig- 3' is an enlarged, longitudinal section on a median. plane, partsbeing shown in elevation for clearness;

Fig. 4 is a top plan view of Fig; 3, but including the portions removedby section in Fig. 3-;

Fig. 5 is a view similar to Fig. 3, but showing the parts in a differentrelative position;

Fig. 6 is a top plan view of Fig. 5, but including the portions removedby section in Fig. 5;

Fig. '7 is an enlarged, fragmentary longitudinal section on a medianplane, of the lower end portion of the tester; and

Fig. 8 is a transverse section on the line 8-8 of Fig. 5.

In the form shown in the drawings for illustrative purposes, andreferring to Figs. 1, 3. and'5, my core hardness tester comprisesgenerally a stem 1 having a cylindrical bore; 2, a supporting element 3fixed onthe top' of the stem, a knurled wheel 4 rotatable on thesupporting element, a shaft 5 rotatable with the knurled wheel butlongitudinally slidable therein, an externally threaded head 6 fixed tothe upper end of the shaft, a. knurled nut threadably mounted on thethreads of the head 6, a cylindrical foot member 8 fixed to the lowerend of the shaft to rotate and slide in bore 2, and abrading point 9fixed eccentrioally to protrude from the lower face of the foot member,an annular ball bearing device ID resting on the upper face of the footmember, a ferrule above the ball bearing device, and a coil compressionspring I2 between the ferrule and the supporting element 3. The tubularstem is of a length to be comfortably held within the grip of one handof the operator. This stem has fixed at its lower end an outwardlyextending flange 13, downwardly and outwardly beveled on its uppersurface and with its bottom face M, as viewed in Figs. 3 and 5, fallingwithin a plane at right angles to the longitudinal axis of shaft 5.Fixed to the lower face M of flange I3, at suitably circumferentiallyspaced points, are any suitable number of short, sharp-pointed pins l5,sufficiently small to be readily embedded a short distance into thesurface of a baked core being tested so as to prevent the tester fromslipping with relation to the core, and yet prevent any penetrationdamage to the core during testing. Three of such points are shown forillustration in Fig. 2.

The supporting element 3 has an outer marginal edg circular in contourand formed its vertical face with a circumferential groove I6 extendingentirely therearound. On its under face, supporting element 3 is formedwith a downwardly extending annular flange ll fixed in any suitablemanner in the top of stem l, to be stationary therewith during operationof the tester. Supporting element 3 is provided with a central openingl8 within which shaft 5 .is rotatable and longitudinally slidable.

porting element but permit free rotation thereon. Three of such studsare shown for illustration, see Fig. 8, but any other number may be usedas desired. Fixed by screw-bolts or the like 2|, to the under face ofsupporting element 3, is a radially extending stationary arm 22, havingits outer end turned upwardly to form an index member 23, the upper endof which flush with the upper face of the knurled wheel 4 and formedwith a radial stationary index line 24. Also formed at a desiredmarginal location on the upper face of knurled wheel 4 is a radial indexline 25 which moves with relation to the stationary index line 24 as theknurled wheel 4 rotates on the supporting element 3.

The externally threaded head 6 is fixed to the reduced diameter portion26 of shaft 5, preferably with a set screw, as indicated at 2'! in Figs.3 and 5, the outer end of this set screw when tight being inside of theouter surfaces of threads 28 of the head, so as to permit the insidethreads 29 of knurled nut 1 to freely pass thereover when the knurlednut is being rotated thereon. When the threaded head 6 is fixed on thereduced end of the shaft, it will be positioned with its lower facebearing against the shoulder 38 formed between the reduced end and themain portion of the shaft. As will be seen in Figs, 3 and 5, theexternally threaded head 6 is formed with only three threads at thebottom portion of its external surface, the remaining portion beingunthreaded and of a diameter slightly less than the root diameter of thethreads thereon, so as to be sure and clear the threads on the inside ofthe knurled nut l. The outer annular corner of the top end of head 6 isbeveled to provide a slanting surface 3| which is of the same angle asthe upper beveled slanting surface 32 at the top of the knurled nut i,so that these two slanting surfaces will form continous, uninterruptedsurfaces when they are brought into registry, as shown in Fig. 3. Forthis purpose the threads on the inside of this nut are terminated aslight distance short of the top of the nut where they merge into aninner cylindrical surface freely rotatable on the unthreaded sideportion of the head 6, and of a diameter slightly greater than that ofsaid unthreaded side portion. This enables a quick detection of theregistry of slanting surfaces 3| and 32.

It is also to be noted that when slanting surfaces 3| and 32 are inregistry, the bottom surface of knurled nut 1 and the bottom surface ofhead 6 fall in the same plane, which, when the abrading point 9 is freeand out of contact with any object, is also the plane of the uppersurface of the knurled wheel 4. At this same time the point of the indexmarker 33, stamped on the slanting surface 3| of the head 6, will pointto the radial line bearing the numbers 0, 50 and as stamped on theslanting surface 32. This latter surface also has stamped around itsinside edge, circumferentially equally spaced marks and numbers from 5to 45, and on its outside edge similar marks and numbers from 55 to 100,for a purpose later more fully explained.

Knurled wheel 4 is also formed with a central opening 34 Within whichshaft 5 is longitudinally slidable but is prevented from rotationtherein by a key member 35 integrally fixed to knurled wheel 4 andseated in key slot 36 over which key member the slot is longitudinallyslidable. In this connection see Figs. 3, 5 and 8. This constructioncauses shaft 5 to be rotated with knurled wheel 4, and to belongitudinally slidable therein. As seen in Figs. 3 and 5, the coilcompression spring I2 is seated at its top end in the recess 3'! formedin the bottom face of the supporting element 3, this spring surroundingshaft 5. At its bottom end spring I2 is seated over the upstandingtubular neck 38 of ferrule II to bear against the lateral annular flange39 thereof.

As seen in Fig. '7, the ferrule H is slidably mounted on the shaft 5 tobe rotatable with relation thereto, and is provided with a downwardlyextending integral sleeve or neck 40, which is loosely inserted withinthe inner circular opening of the annular inner ball-race member 4|,within the latter of which are rollably seated a series of anti-frictionballs 42 which, on their opposite face, rollably contact the annularouter ball-race member 43 which is fixed within the annular-ball-bearingcasing 44 which in turn is slidably mounted within the bore 2 of acaca-54.-

stemil andrests atiitsbottom: on the-foot-mem her 81. The innerball-race member 41 is 1:0 tatably slidable with:v relation. to thebottom flange: of casing 44'." This ballbearing' assembly asdescribedabove, and. indicated generally in Figs. 3: and 5,. at llli, is a.conventional; device obtainable on the market.

The abrasionv member 91 is. a steel pin, adjustably fixed in hole 45.in. the. foot membenit by a. set screw 46; for longitudinal; adjustment.as desired. The bottomen'd" of. this pin is tapered to asharp point 41,see-Fig.7, and is eccentrically located. in foot. member: 8 so thatwhen. shaft 5 isrotatedz under pressure of spring I.2,. this abradingpoint will rotate in.a circle and scratch into a; baked. core against.which: the tester is. posie' tioned. In the position. shown. in Figs 5the shaft 5 has: been rotated. for. three: revolutions, which caused theabrading point. 413'. under: the constant pressure offspring t2, totravel imamcircle' against the surface? of the core. 48' and, during:such travel, dig intosthe bodyof the baked core to a 01250 inch. in.length from where it begins: to

taper to the tipof the point, and thepins I 5 arersharppointed and.merelylong enough to prevent slipping of. the bottom face it of thetesterwhena the knurled. wheel 4. is rotated with theitester pressedagainst the core. The. threads 28 011113116 head 6- are made with a:pitch of one eighth of. an inch, or in other words, eight threads totheinch; This means that one revolution of the knurled nut l will moveit one eighth: of an'inch with. relation torthe' head, and.tworevolutions will: move: it one quarter. of

inchz thereon.

r The operation of-. the device will be under:- stood' fromthe above:description; The maximum hardness value indicated'by the. hardnesstester islOO for zero penetration. When the abrading point moves: downadistance of 0.250: inch,. the hardness of the core is Intermediatevalues cam-be found withinvthese twoextremesras: indi catedby the scale.When. a: reading ofiO is re-- ferred to, it means that: the marker indexpoint 33ionthe slanting surface 31- of. thehead' 6 stands opposite the:0-50-100' lineon'the slantingv surface 32 of. the. knurled nut. 'l,with. these two: slanting surfaces in registry and the bottom faces. ofthe. head' and nut in the same plane andresting om the top surface ofthe knurled. wheeli 4 This means that the tester was pressed. against abaked core. flat surface with: the head: and nut standing at. 0, and:the knurled: wheel. 4 rotated three: revolutions; starting and stoppingwith the fatten-point- 25' of? the-wheel in registry with the indexline: 24- of the index arm 2223 During these. three revolutions the.abrading point 4:! cut intothe-core a. distance: of one-quarter of aninch; with the topof' the taper in the plane of the bottom. face itofthe stem flange l3 as seen in Fig. 7, and with the: bottom faces ofthe head and nutcontacting the upper face of the. wheel,. thus--indicating, that: the. core Wasof 6 0 hardness. A space stillintervenes. between thertop. of the taper of the pin and thebottom faceof the. foot member 8;v to receive any loose particles forced upthereinto by the: abradingi point.

Again,. with the head andinut' standing: at 0 with relation to eachother, and with the? tester pressed against a baked core flat surface,if the. wheel 4 is rotated: three revolutions and: the abrad'ing point.still stands in. the position. shown in. Fig; 3- with no penetrationinto the core, a rotation of the nut l: clockwise. for: two revolutions.will be required, with the Wheel 4 held stationary, in order? to makethe bottom surface: of the nut touch the top surface ofith'e wheel,.which will bring the marker" index point 33 in registry with" the0-50-100 line, thus reading on the outside,v because of thetworevolutions of the nut. This: I00 reading after: two clockwiserevolutions of' the nut indicates that the core being tested is ofmaximum hardness with zero: penetration of the abrading point-Afterthe-three revolutions of the Wheel, preferably in aclockwisedirection, and the clockwise rotation. of the nutuntilzittouches thewheeLwith the. tester during. this time being. pressedagainst the core, the. tester may then'be removed from the core and thereading read on the top of the nut with relation to: the index 33 onthetop of the head 6 Any'interme'diate degrees of penetration of the:abrading point into the core may likewise be read nthe scale,

In other words, to: make a hardnessit'est of any baked core desired tobe: tested, set th pointer or line 25' on the wheel in registry with".the stationary index line 2 4, turn the knurled nut 1 until the twoslanting surfaces are evem; with marker point 33' opposite the zero" onindexf line 0 -50400; place. the tester on a fiat. surf'acrez'v of thecore and hold the.- testerv against the corewdth one. hand'while. the:wheel 4' is turned: clockwise for a total; of; three. completerevolutions; and: with the tester'still held against? the core turnthernut 1 clockwise (to move it downwardly") until it touches the wheel4.. Then lift: the testenfrom the: core and. read. the. hardness: valueon the" dial opposite the arrow on the central head... The insidefigures onthe: dial. are for the first revoluetionof the" nut and. theoutside figures:- are for the second revolution of thenut.

To check theinstrument, see that. the end; of the-'abrading point iseven: with the bottom. ot the: tester when'the dial is. at: 100; Aliareading of 0; when the two slanting surfaces: are in line, theabra-di'ng. point extends 0.250 inch from. the bottom of the instrument;

Hardness.- readingscan be taken. on. horizontal-,1 vertical; orintermediate: surfaces, as well: as in recesses. When therequired'hardness standards are established for a given practice, thecondie tion. of any core can. be determined quickly and easily.

While-it has been stated that abrasion member 9-- is a steel pin,. itisto be understood that thesame is very hard tobe abrasive resistant, orit may be. of any other material sufliciently hard to maintain its sharppoint for long durations 0t. use.

Also while Iv have, for illustrative purposes; shown and described myhardness tester as applied to the testing of the hardness of"bakedfoundry cores, I wish it understood: that it may be employed forthe testing of the hardness: or plaster; plaster-of-P'aris, mortar, softpfasticgand any other: material of. semi-hardness to which it. may be.adaptable.

I claim:

1. A hardness tester, comprising, a stem having a supporting elementfixed to one end, a shaft mounted in said stem and supporting elementfor rotation and longitudinal movement therein, a wheel member rotatableon said supporting element for rotating said shaft, the shaft also beinglongitudinally slidable through the wheel member, a threaded head fixedto the shaft beyond said wheel member, a nut threaded to movelongitudinally on the head, an abrading element eccentrically mounted onthe end of the shaft removed from said head, and a scale on one of saidnut and head and an index marker on the other for indicating the valueof penetration of the abrading element into a surface being tested.

2. A tester as claimed in claim 1, including a spring connected to theshaft and stem for urging the shaft and abrading element in a directionaway from said supporting element at a predetermined pressure.

3. A tester as claimed in claim 2, including a foot member at the bottomportion of said shaft in which said abrading element is fixed, anannular anti-friction device resting on the foot member, and an annularferrule bearing against said anti-friction device and against which saidspring exerts its pressure.

4. A tester as claimed in claim 3, in which said spring is a coil,compression spring surrounding the shaft and bearing against the ferruleat its lower end and against the supporting element at its upper end.

5. A baked foundry core hardness tester, comprising, a tubular uprightstem, a circular supporting element fixed to the top of the stem andhaving a circumferential groove around its outer edge, a wheel memberrotatable on the supporting element and having an annular dependingflange encompassing the outer edge thereof, adjustable and removablemeans at spaced intervals around the circumference of said flange toenter said groove to enable r0- tation of the wheel on the supportingelement but prevent separation thereof, a shaft rotated by rotation ofthe wheel member but longitudinally slidable therein, said shaft beingrotatable in the supporting element and in the stem, an eccentricabrading element mounted in the bottom end of the shaft, said shaftextending above said wheel member and having a threaded head fixedthereto, a nut threadably mounted on the threads of the head, and ascale on one of the nut and head and an index marker on the other, forreading the amount of penetration of the abrading element into a coreafter rotation of the abrading element on the core and when the nut hasbeen screwed down until it touches the wheel member.

6. A tester as claimed in claim 5, in which the supporting element andthe wheel member have respective index marks to enable a predeterminedamount of movement of the wheel member and the abrading element.

'7. A tester as claimed in claim 6, in which a coil compression springencircles the shaft and bears at one end against the shaft and bears atthe other end against the supporting element to exert a predetermineddownward pressure on the abrading element,

8. A hardness tester, comprising, a tubular stem having a supportingelement fixed to the upper end thereof, a wheel member rotatably mountedon said supporting element, a shaft extending into the stem androtatable in the supporting element and rotatable with the wheel member,said shaft being longitudinally slidable through the supporting elementand the wheel member and extending beyond the top of the latter, anexternally threaded head fixed on the top end of the shaft, a nutthreadably mounted on the threads of the head to move up and down withrelation thereto upon rotation of the nut depending on the direction ofrotation, an enlarged foot member fixed on the bottom of the shaft, aferrule on the shaft, an anti-friction device between the ferrule andthe foot member, a coil compression spring bearing against the ferruleat one end and against the supporting element at the other end, and aneccentric abrading point fixed in the lower face of the foot member ofthe shaft.

9. A tester as claimed in claim 8, in which a scale is mounted on thenut to cooperate with in index marker on the head, and an index markeris provided on each of the supporting element and the wheel member toenable counting of the number of full revolutions of the wheel member onthe supporting element.

10. A tester as claimed in claim 9, in which the ferrule is formed witha radially extending flange to seat the ferrule on the anti-frictiondevice, and to receive the thrust of the lower end of the compressionspring.

11. A hardness tester comprising, a stationary tubular stem, a rotatableand longitudinally movable shaft in said stem, an eccentric abradingpoint on the bottom end of said shaft, a wheel for rotating said shaft,the shaft being longitudinally slidable in the wheel and rotatabletherewith, a spring for normally urging said shaft longitudinallydownwardly, and a twopart member on the upper end of the shaft, one partof the two-part member being fixed to the shaft, and the other partthereof being longitudinally movable with relation to said one part tomeasure the value of downward movement of the abrading point whentesting the hardness of a material being tested.

12. A hardness tester, comprising, a tubular stem, a supporting elementfixed to the top of the stem, a shaft rotatably and longitudinallymovable in said supporting element and having a foot member assembly atits lower end, a wheel member rotatably mounted on the supportingelement, resilient means for normally urging said shaft downwardly, adownwardly extending abrading element eccentrically fixed to th lowerface of said foot member assembly to rotate with the shaft, and means onthe top portion of the shaft above the wheel member to indicate thevalue of hardness of an article against the surface of which theabrading element is moved under pressure by rotation of the wheel memberand shaft, the wheel member and the shaft being interconnected forrotation togethe but with longitudinal movement of the shaft withrelation to the wheel member.

13. A hardness tester, comprising, a stationary member, a shaft mountedin the stationary member for rotation and longitudinal movement therein,an abrading member eccentrically mounted on one end of the shaft, aWheel member rotatable on the stationary member and interconnected withthe shaft for providing rotation and longitudinal movement of the shaftwith relation to the wheel member, said abrading member being movablealong a closed circular path a plurality of times when pressed against asurface to be tested during rotation of the shaft.

and means on the tester for measuring the value of the penetration ofthe abrading member into said surface when the abrading member has movedover said path under a predetermined pres- HARRY L. CAMPBELL.

REFERENCES CITED Number UNITED STATES PATENTS Name Date Guillery Mar.24, 1914 Tone Oct. 29, 1918 La. Vercombe Nov. 14, 1922 Craemer Sept. 11,1934 Dietert Sept. 13. 1938 Podesta Jan. 4, 1944

